1. Field of the Invention
This invention relates to a method for fabricating in place a secondary containment system for hazardous liquid escaping from a primary containment system.
2. Description of the Prior Art
A secondary containment system is a system which collects and contains fluids leaking out of another and primary containment system. For example, a primary containment system may store and deliver gasoline at a corner filling station. A secondary containment system would collect and contain that same gasoline if a primary tank or delivery pipe should rupture or otherwise spill the gasoline. A secondary containment system would also catch gasoline which spills when a fill tube runs over while a fuel storage tank is being filled, for example. While the invention is described hereinafter in connection with a gasoline filling station storage and delivery system, it should be understood that the invention may also be used to protect any other suitable primary containment system.
The gasoline dispensers, or, as referred to by the general public, gasoline pumps, in a service station undergo routine maintenance on a regular basis. For example, the filters in a dispenser are typically changed once a month. When the maintenance worker removes an old filter, even though proper care has been taken, a portion of the gasoline present in the dispenser downstream of the filter may drip onto the ground beneath the dispenser. When one considers that this amount may drip from each of the dispensers in a service station on a monthly basis, it is clear that the potential pollution problem may become significant.
Gasoline drainage can also occur when less frequent types of repair work, such as changing the meters, are performed on gasoline dispensers. Therefore, gasoline drainage due to this type of repair work can also pose a significant pollution problem even though it occurs on an irregular basis. Also, dispensers can develop slow leaks at gaskets or other points despite regular maintenance. Such slow leaks allow a steady trickle of gasoline to drain onto the ground.
Accordingly, a need exists for an apparatus and a method for preventing the gasoline draining from gasoline dispensers from polluting the soil or water. It would also be highly desirable for the apparatus involved to be easy to install in existing service stations and to be compatible with existing equipment. Additionally, the method should preferably be adaptable to work with other potential sources of leaking hazardous liquids.
While commonly called "pumps", because these originally were cabinets containing individual pumps for the dispensing of gasoline, this term is now a misnomer, since generally a single separate pump is used to transfer gasoline from a storage tank to a number of gasoline dispensers. The dispenser housings themselves, thus, only contain components for feeding gasoline from a supply conduit to a dispensing hose and nozzle, and certain auxiliary equipment, such as electronic metering and pricing equipment. Gasoline dispenser housings are normally set in a place on a pump box, which is in the form of a metal frame, disposed in the ground, either flush with the surface, usually concrete, of a service station or flush with the surface of an island built in the service station area, the metal frame, open at the top and bottom with a support in the frame to hold a safety valve that is connected at one end to a fuel line, and at the other end to the dispenser. One type of metal frame, or pump box, is a generally rectangular housing, open at both the top and bottom and has four walls with flanges on two of the walls to support the box in a framework. A layer of fill material, typically coarse ground or stone is usually provided beneath the pump box, and concrete is typically poured around the box to enclose the same. Any gasoline that might spill from the dispenser conduit, in the case of a mishap, would thus drain into the fill material and then into the soil below a conventional pump box.
With the advent of more stringent environmental regulations, it is important to attempt to contain any gasoline spillage and prevent passage of such spillage to the ground, where absorption could require removal and treatment of the contaminated ground material. Hence, it is highly desirable to provide a secondary containment system for spillage from a gasoline dispenser. A number of such systems are currently available, and they include sumps, pans, bags or other devices for use under dispensers to catch spills or drips. A common characteristic of all such systems is that they are each pre-fabricated to have the shape necessary to be insertable, and to have a tight fit, under the particular dispenser with which it is to be used. In addition, all such systems must be pre-fabricated so as to have holes and closure fittings therein that are properly sized and positioned to permit the various product piping and electrical conduits associated with the particular dispenser with which it is to be used, to extend through such holes and to be liquid tight so as not to let liquids enter or escape the secondary containment system. The many different dispensers involve many different types and arrangements of product piping and electrical conduits and thus, require many different types of pre-fabricated secondary containment systems.
Thus far, no such secondary containment system is known which can be fabricated in place for all types of gasoline dispensers or for any other primary containment system and can accommodate and form a liquid-tight seal with any configuration of product piping and electrical conduits.